3. From 1980 to 2008, did the amount of carbon monoxide in the air increase, decrease, or
remain the same?
4. Notice that all the percents change value on the graph or negative what does that indicate about the level of the five politise in the air during the period from 1980 to 2003?
5. Which pollutant showed a greater decrease in the emission from 1980 to 2008 Nitrogen oxides or sulfur dioxide